A driving method applied to a liquid crystal display. First, a first pixel voltage is outputted to a first pixel in a first row of pixels to change a transmittance of the first pixel. Next, a second pixel voltage is outputted to a second pixel in a second row of pixels to change a transmittance of the second pixel. Then, a backlight module is turned on. Next, at a first predetermined time point after the first pixel voltage is outputted, a pixel electrode voltage of the first pixel is adjusted. Finally, at a second predetermined time point after the second pixel voltage is outputted, a pixel electrode voltage of the second pixel is adjusted. The second predetermined time point follows the first predetermined time point.
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1. A method for driving a liquid crystal display, the liquid crystal display comprising a back light module and a pixel array having a first row of pixels and a second row of pixels, the method comprising: (a) turning on a thin film transistor of a first pixel in the first row of pixels by a first scan signal and outputting a first pixel voltage to the first pixel in the first row of pixels to change a transmittance of the first pixel, and then outputting a second pixel voltage to a second pixel in the second row of pixels to change a transmittance of the second pixel; (b) turning on the backlight module; (c) adjusting a pixel electrode voltage of the first pixel at a first predetermined time point after outputting the first pixel voltage and before turning on the thin film transistor of the first pixel by a second scan signal next to and occurring immediately after the first scan signal; and (d) adjusting a pixel electrode voltage of the second pixel at a second predetermined time point after outputting the second pixel voltage, wherein the second predetermined time point is subsequent to the first predetermined time point, wherein when the first pixel voltage substantially equals the second pixel voltage, an integration of the transmittance of the first pixel over time in a lighting period of the backlight module is a first light intensity value and an integration of the transmittance of the second pixel over the time in the lighting period of the backlight module is a second light intensity value, and the difference between the first light intensity value and the second light intensity value is substantially smaller than 20% of the first light intensity value.
This invention relates to driving methods for liquid crystal displays (LCDs) to reduce brightness differences between adjacent pixels. LCDs use a backlight module and a pixel array with multiple rows of pixels, each controlled by thin film transistors (TFTs). The problem addressed is the visible brightness variation between adjacent pixels when the same voltage is applied, due to timing differences in pixel charging and backlight activation. The method involves sequentially driving pixels in different rows. A first pixel in a first row is activated by a scan signal, receiving a pixel voltage to adjust its transmittance. After this, a second pixel in a second row is similarly driven. The backlight module is then turned on. To minimize brightness differences, the pixel electrode voltage of the first pixel is adjusted at a predetermined time after its initial voltage is applied but before the next scan signal activates it. Similarly, the second pixel's voltage is adjusted at a later time. The timing ensures that when both pixels receive the same voltage, their integrated light intensity over the backlight's lighting period differs by less than 20%. This compensates for timing-related transmittance variations, improving display uniformity. The method ensures consistent brightness across adjacent pixels despite differences in their activation timing.
2. The method according to claim 1 , wherein the second light intensity value is substantially equal to the first light intensity value.
Building upon the LCD driving method described previously, when both pixels receive the same voltage, the integrated light output (intensity value) of the second pixel is nearly identical to the integrated light output of the first pixel. This aims to achieve very uniform brightness across adjacent rows when displaying the same color or grayscale level.
3. The method according to claim 1 , wherein a first compensation signal is outputted to the first pixel to adjust the pixel electrode voltage of the first pixel in step (c), and a second compensation signal is outputted to the second pixel to adjust the pixel electrode voltage of the second pixel in step (d).
In the previously described LCD driving method, the pixel voltage adjustment involves applying a compensation signal to both the first and second pixels. This compensation signal is specifically designed to fine-tune the voltage level and thus the transmittance of each pixel, improving image quality and reducing artifacts. These signals are applied at the predetermined times for the first and second rows respectively.
4. The method according to claim 1 , wherein the first pixel is coupled to a first common electrode line, the second pixel is coupled to a second common electrode line, a voltage of the first common electrode line is adjusted to directly adjust the pixel electrode voltage of the first pixel in step (c), and a voltage of the second common electrode line is adjusted to directly adjust the pixel electrode voltage of the second pixel in step (d).
In the LCD driving method previously described, the first pixel is connected to a first common electrode line, and the second pixel to a second common electrode line. The voltage on the first common electrode line is directly adjusted to change the pixel voltage of the first pixel. Similarly, the voltage on the second common electrode line is directly adjusted to change the pixel voltage of the second pixel. These adjustments happen at the specific times defined for the first and second rows respectively.
5. The method according to claim 1 , wherein the backlight module is turned on after the transmittance of the first pixel is greater than zero to enter a lighting state, the backlight module is turned off before the transmittance of the second pixel is substantially equal to zero to enter a darkening state, and the backlight module keeps a first luminance in the lighting period of the backlight module.
In the LCD driving method previously described, the backlight is turned on after the first pixel's transmittance becomes greater than zero. The backlight is turned off before the second pixel's transmittance reaches zero. During the time the backlight is on (lighting period), the backlight maintains a consistent brightness. This ensures proper image formation and minimizes motion blur.
6. The method according to claim 5 , wherein the backlight module is turned on after the transmittance of the first pixel is greater than zero and before the second pixel has a maximum transmittance to enter the lighting state.
In the LCD driving method where the backlight is enabled after the first pixel begins transmitting light, the backlight turns on before the second pixel reaches its maximum light transmittance. This specific timing ensures balanced image brightness and contrast, avoiding artifacts caused by mismatched pixel response times.
7. The method according to claim 5 , wherein the backlight module is turned on after the second pixel has a maximum transmittance to enter the lighting state.
In the described LCD driving method, the backlight turns on only after the second pixel has reached its maximum light transmittance. This addresses scenarios where delaying the backlight improves overall image uniformity or reduces power consumption without significantly impacting perceived brightness.
8. The method according to claim 5 , wherein the backlight module is turned off after the first pixel has a maximum transmittance and before the transmittance of the second pixel reaches a minimum to enter the darkening state.
Following the LCD driving method described, the backlight turns off after the first pixel reaches its maximum transmittance, but before the second pixel reaches its minimum transmittance (fully dark). This specific timing strategy helps minimize motion blur and improve the perceived contrast ratio of the display.
9. The method according to claim 1 , wherein the lighting period of the backlight module comprises a first sub-period and a second sub-period, the backlight module keeps a first luminance in the first sub-period, and the backlight module keeps a second luminance in the second sub-period.
In the LCD driving method as described above, the backlight's on-time (lighting period) is divided into two segments: a first sub-period and a second sub-period. The backlight operates at a first brightness level during the first sub-period and a second brightness level during the second sub-period. This allows for dynamic control of the backlight intensity over time.
10. The method according to claim 9 , wherein the first luminance is unequal to the second luminance.
Expanding upon the LCD driving method with segmented backlight control, the brightness of the backlight is intentionally different between the first and second sub-periods. This dynamic adjustment enables various effects such as improved contrast, reduced power consumption, or custom gamma correction.
11. The method according to claim 1 , wherein the lighting period of the backlight module comprises a first sub-period, a second sub-period, and a third sub-period, the second sub-period is between the first sub-period and the third sub-period, the backlight module keeps a first luminance in the first sub-period, the backlight module keeps a second luminance in the second sub-period, the backlight module keeps a third luminance in the third sub-period, and the second luminance substantially equals zero.
In the LCD driving method previously described, the backlight's on-time is divided into three distinct segments: a first, second, and third sub-period. The second sub-period occurs between the first and third. The backlight maintains a first brightness in the first segment, a second brightness in the second segment, and a third brightness in the third segment. The brightness in the second segment is essentially zero (backlight is off).
12. The method according to claim 11 , wherein the first luminance and the third luminance are different.
In the three-segment backlight driving method described previously, the first and third brightness levels are intentionally set to be unequal. This allows for a greater range of control over the perceived brightness and contrast of the displayed image, potentially improving dynamic range.
13. The method according to claim 11 , wherein the first luminance is substantially equal to the third luminance.
Building upon the three-segment backlight control, the brightness levels during the first and third sub-periods are set to be approximately equal. While the middle sub-period has zero brightness, this setup can still offer advantages such as strobing effects or tailored motion blur reduction compared to a constant backlight.
14. The method according to claim 11 , wherein the backlight module is turned on and off more than twice.
The LCD driving method featuring a backlight with multiple segments describes the backlight turning on and off more than two times during the refresh cycle. This allows complex backlight modulation schemes for advanced features like black frame insertion and improved motion handling.
15. A liquid crystal display, comprising: a backlight module; and a pixel array comprising: a first row of pixels and a second row of pixels, a thin film transistor of a first pixel in the first row of pixels is turned on by a first scan signal to receive a first pixel voltage in order to change a transmittance of the first pixel, a second pixel of the second row of pixels receiving a second pixel voltage in order to change a transmittance of the second pixel, the first row of pixels and the second row of pixels being sequentially driven; wherein a pixel electrode voltage of the first pixel is adjusted at a first predetermined time point after the first pixel receives the first pixel voltage and before the thin film transistor of the first pixel is turned on by a second scan signal next to and immediately following the first scan signal, a pixel electrode voltage of the second pixel is adjusted at a second predetermined time point after the second pixel receives the second pixel voltage, and the second predetermined time point follows the first predetermined time point; and wherein when the first pixel voltage substantially equals the second pixel voltage, an integrated value of the transmittance of the first pixel over time in the lighting period of the backlight module is a first light intensity value, an integrated value of the transmittance of the second pixel over the time in the lighting period of the backlight module is a second light intensity value, and the difference between the first light intensity value and the second light intensity value is substantially smaller than 20% of the first light intensity value.
A liquid crystal display (LCD) has a backlight module and a pixel array with rows of pixels. A thin-film transistor (TFT) activates a pixel in the first row via a scan signal, applying a voltage to change its light transmittance. A voltage is applied to a pixel in the second row, also changing its transmittance. The rows are driven sequentially. The first pixel's voltage is adjusted at a specific time after its voltage application, but before the next scan signal triggers its TFT. The second pixel's voltage is adjusted later. When both pixels have the same voltage, the integrated light output of each is measured. The difference should be less than 20% of the first pixel's output.
16. The display according to claim 15 , wherein the second light intensity value is substantially equal to the first light intensity value.
Expanding upon the LCD described above, the integrated light output of the second pixel is essentially the same as the integrated light output of the first pixel when both are driven with the same voltage. This ensures a very uniform display, reducing visible artifacts and enhancing visual quality.
17. The display according to claim 15 , wherein the first pixel is adapted to receive a first compensation signal to adjust the pixel electrode voltage of the first pixel, and the second pixel is adapted to receive a second compensation signal to adjust the pixel electrode voltage of the second pixel.
In the LCD device described previously, the first pixel receives a first compensation signal to adjust its voltage, and the second pixel receives a second compensation signal to adjust its voltage. These compensation signals allow for fine-tuning each pixel's light output to improve overall image accuracy and uniformity.
18. The display according to claim 15 , wherein the first pixel is coupled to a first common electrode line, a voltage of the first common electrode line is adjusted to directly adjust the pixel electrode voltage of the first pixel, the second pixel is coupled to a second common electrode line, and a voltage of the second common electrode line is adjusted to directly adjust the pixel electrode voltage of the second pixel.
The described LCD contains a first common electrode line connected to the first pixel, and a second common electrode line connected to the second pixel. The voltage of the first common electrode line is adjusted to directly change the pixel voltage of the first pixel. Similarly, adjusting the second common electrode line voltage directly affects the second pixel's voltage.
19. The display according to claim 15 , wherein the backlight module is turned on after the transmittance of the first pixel is greater than zero to enter a lighting state, the backlight module is turned off before the transmittance of the second pixel reaches a minimum to enter a darkening state, and the backlight module keeps a first luminance in the lighting period of the backlight module.
In the described liquid crystal display, the backlight is turned on after the first pixel's transmittance is greater than zero, which starts the lighting state. The backlight is turned off before the second pixel reaches its minimum transmittance, starting a darkening state. During the lighting state, the backlight maintains a steady brightness level.
20. The display according to claim 19 , wherein the backlight module is turned on after the transmittance of the first pixel is greater than zero and before the second pixel has a maximum transmittance to enter the lighting state.
Expanding on the described display, the backlight is activated after the first pixel begins transmitting light but before the second pixel reaches its maximum transmittance. This precise timing helps balance brightness and contrast, preventing unwanted visual artifacts.
21. The display according to claim 19 , wherein the backlight module is turned on after the second pixel has a maximum transmittance to enter the lighting state.
In the LCD device described, the backlight turns on only after the second pixel has reached its maximum light transmittance. This specific configuration could be used to optimize power consumption or improve certain image characteristics by delaying the backlight illumination.
22. The display according to claim 19 , wherein the backlight module is turned off after the first pixel has a maximum transmittance and before the transmittance of the second pixel reaches a minimum to enter the darkening state.
The described LCD backlight turns off after the first pixel reaches its maximum transmittance but before the second pixel reaches its minimum (darkest) transmittance. This particular timing strategy aids in minimizing motion blur and maximizing the perceived contrast ratio of the displayed image.
23. The display according to claim 15 , wherein the lighting period of the backlight module comprises a first sub-period and a second sub-period, the backlight module keeps a first luminance in the first sub-period and the backlight module keeps a second luminance in the second sub-period.
In the previously described liquid crystal display, the backlight's on-time is divided into two sub-periods. The backlight is set to a first brightness during the first sub-period and a second brightness during the second sub-period, enabling dynamic backlight control.
24. The display according to claim 23 , wherein the first luminance and the second luminance are different.
Expanding upon the described display with segmented backlight, the first and second brightness levels of the backlight are intentionally different. This allows for fine-tuning the display's characteristics like contrast ratio, power consumption, or gamma response.
25. The display according to claim 15 , wherein the lighting period of the backlight module comprises a first sub-period, a second sub-period, and a third sub-period, the second sub-period is between the first sub-period and the third sub-period, the backlight module keeps a first luminance in the first sub-period, the backlight module keeps a second luminance in the second sub-period, the backlight module keeps a third luminance in the third sub-period, and the second luminance substantially equals zero.
In the described liquid crystal display, the backlight on-time is divided into three sub-periods (first, second, third). The backlight operates at a first brightness in the first sub-period, a second brightness in the second (middle) sub-period, and a third brightness in the third sub-period. The second brightness level is essentially zero (backlight is off).
26. The display according to claim 25 , the backlight module is turned on and off more than twice.
The liquid crystal display previously described featuring the three-segment backlight control involves turning the backlight on and off more than twice during one screen refresh. This implies the implementation of a complex backlight modulation scheme.
27. A method for driving a liquid crystal display, the liquid crystal display comprising a back light module and a pixel array having a first row of pixels and a second row of pixels, the method comprising: (a) turning on a thin film transistor of a first pixel in the first row of pixels by a first scan signal and outputting a first pixel voltage to the first pixel in the first row of pixels to change a transmittance of the first pixel, and then outputting a second pixel voltage to a second pixel in the second row of pixels to change a transmittance of the second pixel; (b) turning on the backlight module; (c) adjusting a pixel electrode voltage of the first pixel at a first predetermined time point to lower a transmittance of the first pixel after outputting the first pixel voltage, after the first pixel reaches a maximum transmittance and before turning on the thin film transistor of the first pixel by a second scan signal next to the first scan signal; and (d) adjusting a pixel electrode voltage of the second pixel at a second predetermined time point to lower a transmittance of the second pixel after outputting the second pixel voltage and after the second pixel reaches a maximum transmittance, wherein the second predetermined time point is subsequent to the first predetermined time point, wherein when the first pixel voltage substantially equals the second pixel voltage, an integration of the transmittance of the first pixel over time in a lighting period of the backlight module is a first light intensity value and an integration of the transmittance of the second pixel over the time in the lighting period of the backlight module is a second light intensity value, and the difference between the first light intensity value and the second light intensity value is substantially smaller than 20% of the first light intensity value.
A method for driving an LCD with a backlight and pixel array. First, a TFT in a first row pixel is activated to apply a voltage, changing the pixel's light transmittance. Next, a second voltage is applied to a second row pixel, changing its transmittance. The backlight is then turned on. The voltage of the first pixel is adjusted at a specific time to *lower* its transmittance after it reaches its maximum and before the next scan signal activates the TFT. The second pixel's voltage is also adjusted to *lower* its transmittance after reaching its maximum. The second pixel's adjustment is later than the first. When both pixels receive the same voltage, the integrated light output of each pixel is measured. The difference between these light intensity values should be less than 20% of the first pixel's output.
28. A liquid crystal display, comprising: a backlight module; and a pixel array comprising: a first row of pixels and a second row of pixels, a thin film transistor of a first pixel in the first row of pixels is turned on by a first scan signal to receive a first pixel voltage in order to change a transmittance of the first pixel, a second pixel of the second row of pixels receiving a second pixel voltage in order to change a transmittance of the second pixel, the first row of pixels and the second row of pixels being sequentially driven; wherein a pixel electrode voltage of the first pixel is adjusted at a first predetermined time point to lower a transmittance of the first pixel after the first pixel receives the first pixel voltage, after the first pixel reaches a maximum transmittance and before the thin film transistor of the first pixel is turned on by a second scan signal next to the first scan signal, a pixel electrode voltage of the second pixel is adjusted at a second predetermined time point to lower a transmittance of the second pixel after the second pixel receives the second pixel voltage and after the second pixel reaches a maximum transmittance, and the second predetermined time point follows the first predetermined time point; and wherein when the first pixel voltage substantially equals the second pixel voltage, an integrated value of the transmittance of the first pixel over time in the lighting period of the backlight module is a first light intensity value, an integrated value of the transmittance of the second pixel over the time in the lighting period of the backlight module is a second light intensity value, and the difference between the first light intensity value and the second light intensity value is substantially smaller than 20% of the first light intensity value.
A liquid crystal display (LCD) has a backlight module and a pixel array with rows of pixels. A thin-film transistor (TFT) activates a pixel in the first row via a scan signal, applying a voltage to change its light transmittance. A voltage is applied to a pixel in the second row, also changing its transmittance. The rows are driven sequentially. The first pixel's voltage is adjusted at a specific time to *lower* its transmittance after it reaches its maximum and before the next scan signal triggers its TFT. The second pixel's voltage is adjusted later, also to *lower* its transmittance after reaching its maximum. When both pixels have the same voltage, the integrated light output of each is measured. The difference should be less than 20% of the first pixel's output.
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July 10, 2007
September 24, 2013
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